In development of ultra large scale integration (ULSI) technology, there has emerged the problem of increased capacitance of intra- and interlayers, causing signal delays. Therefore, many attempts have been made to develop an insulating layer matrix for reducing the capacitance of intra- and interlayers.
For example, U.S. Pat. No. 5,853,808 discloses a composition comprising an organic siloxane polymer and a silsesquioxane polymer; European Patent Publication No. 0 997 497 A1 discloses a composition obtained from a mixture of various alkoxysilanes; and Korean Patent No. 343938 discloses an organic siloxane composition obtained from cyclic siloxane monomers. These organic siloxane polymers may provide insulating films having a relatively low dielectric constant, but, the films thus prepared have poor mechanical properties.
Meanwhile, techniques using a porous silica as a matrix for an insulating film have been suggested (Japanese Patent Application Publication Nos. 1997-315812, 1997-313812 and 2003-249495; U.S. Pat. No. 6,261,357; and European Patent Publication No. 0 992 556 A1): an insulating film is prepared using porous silica particules whose surface is treated with an alkoxy silane, halogenated silane, etc. Also, Japanese Patent Application Publication No. 1999-50007 discloses a silica nanocluster to be used in a low dielectric film. However, the above techniques have disadvantages in that the porosity which affects the dielectric constant of the resulting film is difficult to control.